Backyard Aquaponics
A place to discuss aquaponics

So I finished the bricks and step, and added some lighting.

This is extracted from my post in BOSSs thread:

...I have a DO meter and one of the things on my radar is improving DO in my systems. I already find that DO is much lower than I would like. Two systems - one with catfish (and a few strays), the other with tilapia - water temp in the 70 - 74 °F range. DO is below 4 with the tilapia, and barely over 4 with the catfish. I have a few 18watt air pumps running. In some areas I use air stones and others I just have open-ended tubing to make large bubbles that aggressively agitate the surface. My pumps were running 12 hours a day for the catfish (24/7 for tilapia), but nitrite was climbing so now I'm running 24/7 in both systems.

I just added some 6 watt power heads that move water upward and disturb the surface. In one IBC DO was 4.4 before the power head and 5.6 after (one hour later, meter not calibrated that day). But I do plan to evaluate the impact of fine bubbles vs large bubbles vs power head, etc. As I have lost over 100 fish during power out in warm weather. So I want to make maximum use of the battery backup I have for best aeration, especially if the pumps shut off.

I'll start posting about this in my system thread as it will likely be of interest to others...

Two things today.

1) I just tested my system for DO thus officially starting my aeration test. I have a Milwaukee MW600 DO meter. Calibrated, check. I have everything running so the DO will be at it's highest now. I'll test again in the morning, then start removing different aeration devices and measure DO at the same time of day.

2) So I decided to measure a few other items while I was at it since I rarely test my water for much more than pH. My KH is okay at 90. But I think my GH may be a tad high. I could use some recommendations for lowering it to see what might work best for me. It took 42 drops to turn the water, so that works out to GH of about 750. I'm thinking 150 to 250 would be a lot better for my catfish. My top off water is about 200 GH.

I'm wondering if I can pump the water through a softener with KCL and get the GH down over time. Any recommendations? There are always good ideas here.

Thanks dlf! Good ide for the SLO too. I add a length of pipe along the bottom for my IBC tanks. It seems to keep the square tanks cleaner.

So I completed an uber-scientific DO test. Kinda. Well maybe not. I didn't get the organized discrete data that I planned, as life interfered with urgent tasks, a power outage and some rainy weather. But I did complete two independent tests that gave me a warm fuzzy feeling regarding aeration methods.

I turned off the pump for an extended period and the DO declined to very low levels (below 2.0). For one test I first used coarse bubbles from an open ended air pump and tubing. The 18 watt airpump is split between the test tank and another system, so let's assume near equal distribution and say it was consuming 9 watts (probably more) providing the aeration. The DO rose to 4.4 after two hours and held steady.

Next time in the same IBC I used a powerhead just under the surface pointed upward to lift water above the surface a couple of inches. The DO rose to 5.7 and held steady, using only 6 watts of power.

In a separate IBC I first used a dedicated 18 watt airpump with three 6" airstones and the DO reached 2.7 after one hour. Next I used a 6 watt powerhead and the DO reached 3.8 after one hour.

So given test conditions I prefer the powerhead for DO power watt efficiency and keeping my fish safe during a power outage. However, the complication is tank water level. During normal operation the water reaches an overflow height and is stable. But when the power is out the level drops several inches. This makes the powerhead less effective during normal times and highlights how critical it is to place it properly based on the low-water level present when pumps are not running.

Conversely, in my main system there is no sump, so when power is out the powerhead becomes less effective since the water level rises significantly. I'll need to devise a method to allow the powerhead to remain in a fixed position, but also rise and fall with the water level. Perhaps a float attached to a mount on a hinged arm. I'll work on it and post some photos when I have a good solution.

I had some cool photos and video of the test conditions. Unfortunately the phone containing them decided to hurl itself from my back pocket into a sump tank. CPR was not successful and sadly the phone, and the photos, perished before the contract was expired.

A few improvements over the past several weeks. I finally added a top off system complete with sediment and carbon filters and float valves for each system fed by a pump from my rainwater system. Eventually I will add a float switch in the rainwater system to be sure there is rainwater before starting the pump, and put the top off pump on a regular timer schedule.

Also, I finally dealt with a significant overstocking issue and eliminated a temporary 300 gal extra tank. I graded all my tilapia and only kept 40 fish roughly the same size (8 - 10"). I culled about a dozen smaller ones and harvested all the larger ones. Most are well over 2 lbs with some about 1.5ish. I have no idea how many I have to fillet yet but I estimate about 75, I'll finish them tomorrow. By the way, I drained the water in the cooler to add ice - the fish are not floating in the photo. I filleted three tonight and made a fish stock soup base with the bones. I plan to make a tilapia chowder tomorrow.



I still have (30?) extra 4 - 6" catfish in another temporary 250 gal tank, but at least I don't have to heat that one.

So I have a few photos to share from recent harvests. Winter crops are doing well. The cauliflower took forever to form a head, but after I dug down into all the leaves I had a pleasant surprise. I already ate all the broccoli so no photos of that. I hope everyone else is having a good season (summer down under and winter up here).







Spring is not far away so I'm trying to plan my next round of planting and a long term layout for what to plant where.

Look at you! That is outstanding growth and such a pretty build too. I love the lights too.

Thank you Brian. I found some better photos of the lights. It's a very special place in the evening - a great place to just keep busy doing nothing (and very often work hard). I am so addicted to AP and so glad I discovered it. I truly enjoy sharing with my family and others.

I managed an overhead shot this afternoon from the tree house platform. It still doesn't do justice but it gives a great idea of the layout. The catfish tank is under the shade cloth cover. It's a roll-up window screen so when I want to uncover it I just turn the crank and retract the cover.

Very nice layout with the lights and everything there John.
Can you please tell me what is the cost of heating the water in winter temps. I assume you have tilapia and cat fish.

It is a beautiful backyard, you need an award for sheer beauty and serenity.

I use a 1500 watt electric heater. My IBC tank is insulated with 2" urethane foam on all 6 sides and has 6 growbeds totaling about 200 gallons of volume. Here is the usage data for the past week in cost, kWh and then an hourly graph for kWh. I have solar electric so I'm not actually paying the prices shown. Even so, I did purchase a propane water heater and I plan to eliminate the electric heater, or at least use it for emergencies only.




I use a Wiser smart switch that tracks electric consumption and the graphs are from the website / app associated with the device.

Thanks for the kind words Brian. I have great inspiration form you, Faye, Ronmaggi, and many other systems on this forum. I'm very lucky to enjoy an outdoor system in the southern California climate.

Cool, thanks for the info. This is after solar sold back into the grid, is that right?